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目前我国测定碱土金属碳酸盐中碳、氧同位素制样,多采用在真空条件下,用100％浓度的磷酸与碱土金属的碳酸盐反应,制备出供质谱仪分析的CO_2气体。 由于市售磷酸浓度为85％,必须通过脱水才能达到要求。以往的磷酸脱水法是加入五氧化二磷,由于该法产生放热反应,在反应过程中受热不匀,易使容器破裂;且制得的磷酸必须经42℃予热后才能使用,给工作带来许多不便。为此我们采用在畅通氮气的情况下,直接加热至300℃脱水,方法简便
At present, China’s determination of carbon and oxygen isotopes in alkaline earth metal carbonate preparation, and more use of vacuum conditions, with 100% concentration of phosphoric acid and alkaline earth carbonate carbonate reaction, prepared for mass spectrometer analysis of CO_2 gas. As the market concentration of phosphoric acid is 85%, we must meet the requirements through dehydration. In the past, the phosphoric acid dehydration method was to add phosphorus pentoxide. Because this method produces an exothermic reaction and is heated unevenly during the reaction, it is easy to rupture the container. The obtained phosphoric acid must be preheated at 42 ° C. to work Bring a lot of inconvenience. To this end, we use the case of unimpeded nitrogen, directly heated to 300 ° C dehydration, the method is simple